THE SPEEDOMETER STOPS WORKING WHEN IT GETS HOT ON MY 2004 TRAIL BLAZER THANKS.

This is a pretty common issue for Trailblazers to have. Here's a link with more information about these GM gauge problems. And where you can purchase replacement parts on Amazon if you want to do the repair yourself. How To Repair My Instrument Cluster

For speedometer problem click the link below :---

How to trouble shoot speedometer?

http://schematicsdiagram.blogspot.com/2011/06/speedometer-not-working.html

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speedometer not working?

http://technoanswers.blogspot.com/2012/01/1996-fiat-bravo-speedometer-not-working.html

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Speedometer runs backward?

http://technoanswers.blogspot.com/2012/01/speedometer-runs-backward.html

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Warning lights on and speedometer died?

http://howtobyme.blogspot.com/2011/08/warning-lights-on-and-speedometer-died.html

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ABS & Brake lights warning indicator steady on dash and speedometer not working?

http://howtobyme.blogspot.com/2011/11/abs-brake-lights-warning-indicator.html

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Odometer works properly but speedometer works intermittently?

http://technoanswers.blogspot.com/2012/01/odometer-works-properly-but-speedometer.html

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speedometer is jumping?

http://schematicsdiagram.blogspot.com/2012/01/isuzu-rodeo-speedometer-is-jumping.html

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This will help.

Thanks.

If everything else works ok, the vehicle drives normally, and all the other gauges are working then you may have a bad speedometer servo motor. This servo is what actually moves the speedometer needle to match the speed you are driving at. The cluster would need to come out and be repaired to fix this problem if this is the case.